[unreadable] Our goals in Phase I have been completed and showed the feasibility of our approach. We applied Near-Infrared Spectroscopy (NIRS), a non-invasive method and an affordable, portable, bedside technique for the diagnosis of the degree of the hypoxic insult in the brain, in sleep apnea, during daytime napping. It has been suggested that chronic, recurrent hypoxia during sleep leads to brain injury, which causes neuropsychological deficits and decline of cognitive function. Cerebrovascular accidents, including fatal strokes are not uncommon. Conventional polysomnography, a relatively expensive test, detects sleep apnea at various sleep stages and determines arterial oxygen saturation. However, current clinical methods do not provide information on brain oxygenation, which is important especially in subjects with preexisting anatomical or functional vascular pathology. NIRS enables continuous real-time measurements of changes in the hemoglobin oxygenation and blood volume, thus providing information on tissue oxygenation and hemodynamics. In Phase II we propose the development of a tool and the application of NIRS to determine cerebral hemodynamics during sleep, in association to overnight polysomnographic sleep studies. Our goal is the development of reliable, cost efficient instrumentation for early detection of cerebral hemodynamic abnormalities in sleep apnea, for the prevention of hypoxic cerebral morbidity and mortality. [unreadable] [unreadable]